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Thread: Jandy LT400

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    Jandy LT400

    Good morning

    So down to it, the problem that is!

    I just purchased a used Jandy LT400 from a friend. I have it plumbed and wired...

    When I first turned it on, it went through diagnostic, then threw a pressure switch light... so I replaced it.

    Tried again...still have the pressure light flashing... so I turned down the thermostat on the pool side...and the light stayed off. As I turned the knob towards the red, there was a small click, and the light came on and started flashing. I repeated this process multiple times...

    Could use some help here... Thanks so much in advance!

    James
    Pool Noob
    16000 Gal Inground
    Jacuzzi Magnum Pump
    Sand Filter
    Jandy LT400 Heater

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    Re: Jandy LT400

    The pressure switch light does not indicate that it is bad. It indicates that the pump pressure is not sufficient to close the contacts and allow the heater to fire. You may need to use a higher speed on the pump if possible to get the switch to close.
    Unknown make 18' above ground (bought used in 1999) Sparco sand filter. Hayward 100,000 BTu heater. 2 speed pump

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    Re: Jandy LT400

    Also make sure your filter is clean, and the baskets too!

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    Re: Jandy LT400

    Filter basket is spotless...well, not spotless...its old...old things have spots...Im old, I have spots...

    I just replaced the motor, its a 53J (I think) 1HP motor...

    Flow through the copper tubing is strong, its got to be more that 2psi... No?

    Quote Originally Posted by danpik View Post
    The pressure switch light does not indicate that it is bad. It indicates that the pump pressure is not sufficient to close the contacts and allow the heater to fire. You may need to use a higher speed on the pump if possible to get the switch to close.
    Pool Noob
    16000 Gal Inground
    Jacuzzi Magnum Pump
    Sand Filter
    Jandy LT400 Heater

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    Re: Jandy LT400

    With the power off and one wire unhooked from the pressure switch, Turn the pump on and measure the resistance across the two contacts on the switch to see if it is closing. Paul may see this and comment on it as well. May be something in the inlet of the heater not allowing enough flow.
    Unknown make 18' above ground (bought used in 1999) Sparco sand filter. Hayward 100,000 BTu heater. 2 speed pump

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    Re: Jandy LT400

    Thanks for that, will do that and post the numbers. It will have to wait until a bit later, new liner is being installed as we speak/type/whatever...

    Quote Originally Posted by danpik View Post
    With the power off and one wire unhooked from the pressure switch, Turn the pump on and measure the resistance across the two contacts on the switch to see if it is closing. Paul may see this and comment on it as well. May be something in the inlet of the heater not allowing enough flow.
    Pool Noob
    16000 Gal Inground
    Jacuzzi Magnum Pump
    Sand Filter
    Jandy LT400 Heater

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    Re: Jandy LT400

    Is the service light coming on? Is there any type of automation on this system? If so, This is a normal display when a device connected to the “Fireman Switch” operates to open the safety circuit on the heater.
    Paul
    http://www.gastekservices.com A word of caution: When working with gas and electrical you might want to consider a licensed contractor. Consider the value of your life and others around you. If you would like to provide a review of the help I provided, please use the following link to leave a review. gastek - Google Search,

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    Re: Jandy LT400

    No service light. I won't be able to work on this until the installers come out this morning and pull the blowers and cut in the skimmer drain and nozzles... I'm pacing around my deck...lol
    Pool Noob
    16000 Gal Inground
    Jacuzzi Magnum Pump
    Sand Filter
    Jandy LT400 Heater

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    Re: Jandy LT400

    .02 Ohms with one wire detached. Its very odd, the pressure switch light doesnt come on, until I turn up the temperature knob. It does it at the same place every time.

    Quote Originally Posted by danpik View Post
    With the power off and one wire unhooked from the pressure switch, Turn the pump on and measure the resistance across the two contacts on the switch to see if it is closing. Paul may see this and comment on it as well. May be something in the inlet of the heater not allowing enough flow.
    Pool Noob
    16000 Gal Inground
    Jacuzzi Magnum Pump
    Sand Filter
    Jandy LT400 Heater

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    Re: Jandy LT400

    Anyone have any ideas on this? I can hire a tech I suppose, but if no one has an idea here...he/she most likely won't either... Lol
    Pool Noob
    16000 Gal Inground
    Jacuzzi Magnum Pump
    Sand Filter
    Jandy LT400 Heater

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    Re: Jandy LT400

    You say you purchased it used. Do you know if the previous owner had it hooked into any type of automation system?
    Paul
    http://www.gastekservices.com A word of caution: When working with gas and electrical you might want to consider a licensed contractor. Consider the value of your life and others around you. If you would like to provide a review of the help I provided, please use the following link to leave a review. gastek - Google Search,

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    Re: Jandy LT400

    Quote Originally Posted by Hollywood151 View Post
    .02 Ohms with one wire detached. Its very odd, the pressure switch light doesnt come on, until I turn up the temperature knob. It does it at the same place every time.
    That is almost no resistance so I would say the pressure switch is closing. Does the resistance change when you cut the pump off? It should go up high or show the infinity symbol on the screen (or what ever the meter shows for open circuit)
    Unknown make 18' above ground (bought used in 1999) Sparco sand filter. Hayward 100,000 BTu heater. 2 speed pump

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    Re: Jandy LT400

    I do not know, but my assumption is no. It was a pretty clean disconnect. Safety loop is in place and there are no extra wires nor any connections missing.
    Quote Originally Posted by ps0303 View Post
    You say you purchased it used. Do you know if the previous owner had it hooked into any type of automation system?
    - - - Updated - - -

    It does change when the pump is turned off.

    Anyone need an LT400 for parts? I'm frustrated, I cant seem to find another occurance where turning up the temperature knob makes the pressure switch light come on.

    Quote Originally Posted by danpik View Post
    That is almost no resistance so I would say the pressure switch is closing. Does the resistance change when you cut the pump off? It should go up high or show the infinity symbol on the screen (or what ever the meter shows for open circuit)
    Pool Noob
    16000 Gal Inground
    Jacuzzi Magnum Pump
    Sand Filter
    Jandy LT400 Heater

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    Re: Jandy LT400

    Have I officially stumped the entire forum? I always knew I wanted to be famous...just not for something like this!
    Pool Noob
    16000 Gal Inground
    Jacuzzi Magnum Pump
    Sand Filter
    Jandy LT400 Heater

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    Re: Jandy LT400

    Just my two cents ...... sell it, give it away, junk it ....... save the hassles .... and buy a new one. You mentioned you are already frustrated and it seems that you are having some other work done so add another $1K to the renovation.
    20x32 in ground gunite with white plaster, 17,000 gal apx. kidney shape, and spa attached, solar, 6 panels 4x10, pentair equipment: pump intelliflo vs 8x160VS, cartridge filter 420sq, gas heater, master temp 400k but, easy touch system pool/spa 4sc-ic40/ with salt system, easytouch wireless controller 4 circuit and Rebel auto cleaner. Taylor K 2005-C completed June 2015.

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    Re: Jandy LT400

    Post pics of the board and wiring

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    Re: Jandy LT400

    Before it was unhooked from your friends pool/spa, did you make sure it worked?

    Sorry Ive been busy on another business venture I am starting up.
    Paul
    http://www.gastekservices.com A word of caution: When working with gas and electrical you might want to consider a licensed contractor. Consider the value of your life and others around you. If you would like to provide a review of the help I provided, please use the following link to leave a review. gastek - Google Search,

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